The main-function regionalization is a course of judging the properties of nature and economy and then classifying them. Fuzzy clustering method is the optimization technology that may be used to create fuzzy matrix and ensure clustering relation by subjection according to the properties. The idea of fuzzy clustering is introduced in the land classification based on the regional landuse and nature economic society indexes. By taking Jiangsu Province for an example, the main functions of the region are divided into priority development zone, key development zone, and rest ricted development. Result from the study shows that the method is practical and effective.